Lithographic production is useful for integrated circuits, masks, reticles, flat panel displays, micro-mechanical or micro-optical devices and packaging devices, e.g. lead frames and MCMs. Lithographic production may involve an optical system to image a master pattern onto a workpiece from a spatial light modulator (herein, “SLM”) controlled by a computer. A suitable workpiece may comprise a layer sensitive to electromagnetic radiation, for example visible or non-visible light.
Said computer controlled SLM may be a spatial light modulator (SLM) comprising a one or two dimensional array or matrix of reflective movable micro mirrors, a one or two dimensional array or matrix of transmissive LCD crystals, or other similar programmable one- or two-dimensional arrays based on gratings effects, interference effects or mechanical elements (e.g., shutters).
In general, these computer controlled SLMs may be used for the formation of images in a variety of ways. Said SLMs, include many modulating elements, in some instances, a million or more elements. For example, a problem with SLMs is that the individual elements of a given SLM most probably do not exhibit identical characteristics; e.g., they may have different reflectivity, or they may respond differently to equivalent control signals. These variations in the characteristics of the individual elements of a computer controlled SLM have limited the resolution and accuracy available for their use in optical imaging; e.g., the production of printed patterns on a workpiece has been limited as to its line width and accuracy.
Therefore, there is a need in the art for a method enabling the compensation of computer controlled SLMs, to correct for the effects caused by variations among their individual elements, in order to improve their utility in optical imaging applications